Predator-Prey Games in Multiple Habitats Reveal Mixed Strategies in Diel Vertical Migration

Abstract

Online enhancements: appendix. Dryad data: http://dx.doi.org/10.5061/dryad.19n37d1.abstract: Prey and predators continuously react to each other and to their environment, adjusting their behavior to maximize their fitness. In a pelagic environment, organisms can optimize their fitness by performing diel vertical migrations. We applied a game-theoretic approach to investigate the emergent patterns of optimal habitat selection strategies in a multiple-habitat arena. Our setup allows both players to choose their position at day and at night in the water column. The model reproduces features of vertical migrations observed in nature, including residency at depth or at the surface, vertical migrations, mixed strategies, and bimodal distributions within a population. The mixed strategies appear as a consequence of frequencydependent processes and not of any intraspecies difference between individuals. The model also reveals a curious feature where natural selection on individuals can provoke distinct regime shifts and precipitate an irreversible collapse in fitness. In the case presented here, the increasing voracity of the predator triggers a behavioral shift in the prey, reducing the fitness of all members of the predator population.

Trophic interactions drive the emergence of diel vertical migration patterns: a game-theoretic model of copepod communities

“…The vertical distribution of phytoplankton (and microzooplankton) is prescribed with a typical profile-high in the surface and depleted at depths [16], while all other organisms in the model can adjust their position in the water column freely at day and at night. The goal of an organism's DVM strategy is to maximize its fitness, which is defined as a trade-off between growth and mortality [17,18].…”

“…We also make the simplifying assumption that active feeding copepods constitute about 65% of the smallest size classes (total length 1 mm) but almost 100% of the largest (total length 1 cm), consistent with observations reported in a copepod database [15] (see electronic supplementary material, S1 for more details). The vertical distribution of phytoplankton (and microzooplankton) is prescribed with a typical profile-high in the surface and depleted at depths [16], while all other organisms in the model can adjust their position in the water column freely at day and at night. The goal of an organism's DVM strategy is to maximize its fitness, which is defined as a trade-off between growth and mortality [17,18].…”

“…The Nash equilibrium is derived using the replicator equation [16,24]. In short, the replicator equation allows each subgroup of individuals following a particular strategy to grow proportionally to its corresponding fitness.…”

Large Pelagic Fish Are Most Sensitive to Climate Change Despite Pelagification of Ocean Food Webs

“…As such, we expect that the FEISTY predictions of forage fish biomass incorporates both epi-and mesopelagic fish. How the biomass is distributed between the two groups will depend on the vertical migration behavior of these fish types, their prey, and their predators (Pinti and Visser, 2019). This work is currently under investigation.…”

Two hundred years of zooplankton vertical migration research

“…Further, since individual motivations for behavioural decisions may be rooted in the genetic material (Häfker et al ., 2017), molecular genetic studies should be prioritised to formulate a comprehensive theory on the proximate control of zooplankton vertical migrations. There is also a growing need to explore the community and ecosystem consequences of vertical migrations, both under present and future environmental contexts, as vertical migrations are connected across trophic levels through predator–prey interactions (Bollens et al ., 2010) including complex game‐type interactions (Pinti & Visser, 2019) and perform a crucial role in the buffering of human‐mediated global climate change (Brierley, 2014; Record et al ., 2018).…”